The present invention is generally directed to fluid valves and more particularly to an improved ball valve unit of the type which includes a rotary ball valve member.
Ball valves are well known in the art and generally include a body incorporating a valve chamber and at least a pair of passages communicating with the valve chamber, a spherically shaped rotary ball valve member having a through channel for connecting the passage together when in the open position, and a pair of seats on opposite sides of and engaged with the rotary valve member, between the valve and the body passages to provide a seating action. Such valves have been found to exhibit improved operating characteristics over other conventional forms of valves, such as plug valves. The improved operation of such ball valves is generally due to the fact that a uniform load results over the sealing area. This not only provides an effective seal, but also reduces wear on the sealing components over an extended period of use. Another factor owning to their improved operation is that as the fluid line pressure increases across the rotary valve, the sealing action of the sealing components is intensified. As a result of the foregoing, ball valves have been found to provide a generally all around better sealing action than other conventional forms of valves.
One form of ball valve which has found wide general acceptance is fully described and claimed in U.S. Pat. No. 3,168,279 which issued on Feb. 2, 1965 in the name of John Harry Anderson and Werner K. Priese and which is assigned to the assignee of the present invention. The ball valve there described and claimed include a generally spherically shaped rotary valve or ball member located within a valve chamber between a pair of annular seats which are arranged to form a sealing wedge in which the rotary valve is contained. It has been found that the seal resulting from the wedge-like action provides a very effective seal between the rotary valve and the seats and between the seats and the valve body. The foregoing ball valve has not only been proved to provide effective sealing, but also has been found to maintain effective sealing action over a long service life without adjustment being required to maintain optimum engagement of the valve ball with its coacting valve seats.
Although the ball valves of the prior art have proven worthy of commercial acceptance, there still remains room for improvement. For example, because the rotary valves must be rotated approximately 90 degrees between an open and closed position, less than maximum seal tightness normally must be maintained to allow the valve to be operated. As a result, it is therefore possible for the fluid products being controlled to flow into the valve chamber and critical seal areas between the rotary valve members and the valve sealing components when the valve is in fully open or fully closed position. Over a period of time, the fluid products may solidify, leaving trapped foreign particles or residue which may cause leakage through abrasion, erosion, and corrosion of the valve components in the critical seal areas or the deposits may preclude the opening or closing of the valve. Hence, there is a need for a ball valve wherein maximum seal tightness may be maintained between the rotary valve and the seal components when the valve is in the open or closed condition and wherein the seal tightness may be decreased to a point where the valve may be operated but not to such an extent that large clearances are occurring between the rotary valve member and the valve sealing components.
There are numerous applications for valves wherein it is essential that the fluids on opposite sides of the valves not be mixed when the valve is in the closed condition. One such application is found in the petroleum industry wherein a manifold is used in a piping system with both gasoline and kerosene being handled by the manifold. It is very important that the gasoline and kerosene not be intermittently mingled and traditionally, "block and bleed" valves have been used to prevent such inadvertent mixing. While conventional ball valves have generally been useful in this form of application, there is a resultant need for an improved ball valve to perform this function.
Valves also find considerable use in the food processing industry such as, for example, in the manufacture of candy products. In this application, a valve is called upon to control the flow of relatively hot syrup which will solidify when allowed to cool. A problem therefore exists with any type of ball valve because during closing, the liquid product will accumulate in the space about the rotary valve member and within the rotary valve member through channel. Subsequent cooling of the trapped product eventually results in solidification of the product and possible blockage within the valve. Hence, it is vitally important that a ball valve used in such an application be provided with a flushing system for flushing out the trapped product around the rotary valve member or for maintaining the product in the fluid state by a fluid circulating system.
Lastly, it is often desirable to detect when a valve is leaking. It is often necessary to be able to determine the extent of such a leak to form a basis for replacing the critical seal components. Hence, a ball valve to be used in various applications should be provided with a means by which a seal leak and the extent thereof may be detected.
It is therefore a general object of the present invention to provide a new and improved ball valve unit which is adapted to control the flow of various forms of fluids and in various forms of application.
It is a further object of the present invention to provide a ball valve unit which maintains a maximum tight seal when in the open or closed condition and which includes means for decreasing the seal tightness to an extent permitting easy operation of the valve between the open and closed condition but not to such an extent that large clearances are occurring between the rotary valve and the valve seal components.
It is a more specific object of the present invention to provide a ball valve unit which precludes foreign particles from being trapped in critical seal areas to avoid deleterious effects to the critical seal components such as abrasion, erosion, and corrosion to the ultimate end of extending the useful life of the valve without requiring replacement of seal components or adjustment.
It is a still further object of the present invention to provide such a ball valve unit which includes means for flushing the valve of fluid which solidifies upon cooling or for maintaining such fluids trapped in the valve chamber and in the rotary valve member through channel when in the closed position in the fluid state.
It is a more particular object of the present invention to provide a ball valve unit which precludes inadvertent mixing of the fluids on opposite sides of the valve and which provides a means by which seal leaks may be detected and the extent thereof determined.
The illustrated embodiment of the present invention provides a ball valve unit including a body means defining a valve chamber and a pair of passages having respective openings communicating with the valve chamber, seal support means comprising substantially flat annular surfaces about said passage openings with the surfaces converging in a first direction, and a single trunnion mounted rotary valve or ball means within said valve chamber including a through bore for connecting the passages when in an open position. The ball valve unit further comprises annular seal or seat means disposed between the seal support means and the rotary valve means for establishing a fluid seal therebetween and means for rotating the rotary valve between an open and closed position. The ball valve unit still further includes means coupled to the rotary valve or ball means for moving the rotary valve means in said first direction for increasing the seal between the rotary valve means and the annular seal means when the valve means is in the open or closed position, and for moving the rotary valve means in a second direction opposite the first direction for decreasing the seal to allow the rotary valve means to be rotated between the open and closed positions.